After this unusually cold winter and blizzards the past couple weekends, I think we’re all ready for the ice to come off the lakes! The last couple weeks we’ve been in that in-between time when we can’t start boating on the lakes because the ice is still on them, but the ice isn’t safe to walk on anymore. [Read more…]
These articles explain lake concepts in layman's terms. Lake Associations are welcome to publish these articles in their newsletters and websites as long as they give RMBEL credit.
May 2, 2013 By
Comparing Lakes – the human factors, part 2
There are many factors that go into evaluating a lake. Once you understand some of these factors, you should have a better understanding of your lake, where it came from and where it’s headed.
There are natural factors that contribute to a lake’s condition, and in most cases around here, there are also human factors that have affected the lake. Last week I explained the natural factors. This week, I’ll explain the human factors that affect lakes. [Read more…]
May 2, 2013 By
Comparing Lakes, part 1 – the natural factors
There are many factors that go into evaluating a lake. Once you understand some of these factors, you should have a better understanding of your lake, where it came from and where it’s headed.
There are natural factors that contribute to a lake’s condition, and in most cases around here, there are also human factors that have affected the lake. This week I’ll explain the natural factors since those came first. Next week I’ll explain the human factors and then put them together. [Read more…]
May 2, 2013 By
When and how do lakes freeze over?
Now that it’s too cold to swim in our lakes, we can look forward to the next great lake season – winter sports! Bring on the cold and snow so we can ski, skate, snowshoe, ice fish and snowmobile.
This week, I noticed that some small ponds have a thin layer of ice on them. This prompted me to think abo
ut when and how our lakes freeze over in this area.
As you all know, water freezes at 32 degrees Fahrenheit. That doesn’t mean, however, when the air temp reaches 32 the lakes freeze. Water is a great insulator and good at holding heat, which is why the lake temperature doesn’t fluctuate much day to day like the air does. Therefore, below freezing temperatures are needed for a week or more to form ice on a large lake.
As I have mentioned before, water is a unique substance in that the solid form (ice) is lighter than the liquid form (water). For most substances, the solid form is heavier. Our lives would be much different if ice sank instead of floated. If ice sank, lakes would freeze from the bottom up and the fish and other aquatic creatures wouldn’t survive the winter! [Read more…]
May 2, 2013 By
Shallow Lakes: an important yet vulnerable habitat
Over the summer I have touched on the concept of shallow lakes in other columns, but this week I will focus on them. Shallow lakes behave differently and have different dynamics than deep lakes. Before we go any further, let’s define “shallow”. Shallow lakes are lakes where the sunlight can reach the bottom. Generally, this corresponds to 10-15 feet deep or less. Since the sunlight can reach the bottom, plants are able to grow there.
There are over 5,000 shallow lakes in Minnesota that are over 50 acres in size. These lakes are a very valuable habitat for wildlife, and are also very vulnerable to human impact. [Read more…]
May 2, 2013 By
Lake Trophic States
Scientists like to classify lakes and give names to the different lake types so they can be easily referred to. Trophic states are based on lake fertility. The root “trophy” means nutrients; therefore, lakes are classified based on the amount of available nutrients (Phosphorus and Nitrogen) for organisms. More fertile lakes have more nutrients and therefore more plants and algae. [Read more…]
May 2, 2013 By
Trophic State Index
TSI is a standard measure or means for calculating the trophic status or productivity of a lake. More specifically, it is the total weight of living algae (algae biomass) in a waterbody at a specific location and time. Three variables, chlorophyll a, Secchi depth, and total phosphorus, independently estimate algal biomass.
Phosphorus, Chlorophyll-a (algae concentration) and Secchi depth are related. When phosphorus increases, that means there is more food available for algae, so algal concentrations increase. When algal concentrations increase, the water becomes less transparent and the Secchi depth decreases. [Read more…]